By the time a document is ready to be proofread, it should have been edited already. This means its content should already be well organized, well written, and easy to understand. Editing also involves removing errors, but it focuses more on making sure the document makes sense as a whole.

Proofreading, on the other hand, is about finding errors both small and large that were either missed or introduced during editing. Proofreaders ensure that the document's final draft is completely free of grammatical errors (e.g., subject–verb agreement problems, incorrect word choices, improper punctuation usage, and incorrect spelling) as well as formatting and typographical errors. They also make sure the document adheres to the chosen style guide.